Arrangement for securing a body

ABSTRACT

The invention relates to an arrangement for securing a body made of an anisotropic material, the fibers of which are arranged essentially in an anticipated direction of application of a load. The arrangement consists of an outer casing made of a rigid material relative to the material of the body, into which outer casing one end of the body is capable of being introduced, and a wedge device arranged in the aforementioned direction and capable of being introduced into the aforementined end so arranged upon being introduced to cause the end of the body to expand and in so doing to force its peripheral surface against the walls of the outer casing. Characteristic features of the invention are that the moduli of elasticity, E ij , the moduli of shearing, G ij , and the indices of transverse contraction, V ij , of the wedge are substantially identical with those of the body in the longitudinal and transverse directions and in thickness.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an arrangement for securing a body madeof an anisotropic material, the fibres of which are arranged essentiallyin an anticipated direction of application of a load, consisting of anouter casing made of a rigid material relative to the material of thebody, into which outer casing one end or edge of the body is capable ofbeing introduced, and a wedge device arranged in the aforementioneddirection and capable of being introduced into the aforementioned end oredge, so arranged upon being introduced as to cause the end of the bodyto expand and in so doing to force its peripheral surface against thewalls of the outer casing.

2. Description of Related Art

Such arrangements of a previously disclosed kind are concerned primarilywith the problem of providing a means of securing a wire or a splice inan electrical conductor, that is to say the bodies which are to besecured are in the form of a metal structure. An end connection for awire is previously disclosed in U.S. Pat. No. 3,160,924, for example,and SE.A.163,353 describes an arrangement for the splicing of electricalcables. An end connection or splice of this kind exhibits totallyacceptable tensile strength in the case of an end connection for a steelwire or a splice in a copper conductor.

SUMMARY OF ART PROBLEMS

When the body is of an anisotropic material, it has been found that aconnection provided in a conventional fashion will withstand a loadwhich is unacceptably low in many applications, which could possiblyexplain the comparatively infrequent use of combinations ofunidirectional reinforced plastics and an arbitrary metal structure. Thefollowing has been established through tensile testing: if the tensilestrength of a homogeneous bar of an anisotropic material, such as aunidirectional reinforced plastic, is taken to have the value 1, abolted or rivetted connection will provide a tensile strength of0.2-0.4, whereas a connection of the kind referred to by way ofintroduction using a wedge made of metal will provide a tensile strengthof 0.5-0.6. This comparatively low value can be attributed to the factthat the stresses in the anisotropic material are concentrated at thetip of the wedge, which constitutes a fracture initiation point andresults in the breaking of the fibres, initially at this point andsubsequently in a plane running transversely to the aforementionedpoint.

DESCRIPTION OF PREFERRED EMBODIMENT

The present invention makes available a connection of the kind referredto by way of introduction which will withstand a higher loading thanthat which has previously been achieved, namely of the order ofmagnitude of 0.85-0.95 of the tensile strength of a homogeneous bar,this being permitted in accordance with the invention in that the moduliof elasticity, E_(ij), the moduli of shearing, G_(ij), and the indicesof transverse contraction, v_(ij), of the wedge being used in theinvention is substantially identical with those of the body in thelongitudinal and transverse directions and in thickness.

Approximately uniform material stresses are achieved through theinvention, that is to say no concentration of material stresses ispresent at the tip of the wedge, and thus no fracture initiation point.

I claim:
 1. A means for securing a body made of an anisotropic material,the fibres of which are arranged essentially in an anticipated directionof application of a load, comprising an outer casing made of a rigidmaterial relative to the material of the body, into which outer casingone end of the body is introduced, and a wedge device arranged in theaforementioned direction and introduced into the aforementioned end tocause the end of the body to expand so as to force its peripheralsurface against the walls of the outer casing, characterized in that themoduli of elasticity, E_(ij), the moduli of shearing, G_(ij), and theindices of transverse contraction, v_(ij), of the wedge aresubstantially identical with those of the body in the longitudinal andtransverse directions and in thickness.